Class: JSON::LD::Context

Inherits:
Object
  • Object
show all
Includes:
Utils
Defined in:
lib/json/ld/context.rb

Defined Under Namespace

Classes: TermDefinition

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Utils

#as_resource, #blank_node?, #index?, #list?, #node?, #node_reference?, #value?

Constructor Details

#initialize(options = {}) {|ec| ... } ⇒ Context

Create new evaluation context

Parameters:

  • options (Hash) (defaults to: {})

Options Hash (options):

  • :base (String, #to_s) —

    The Base IRI to use when expanding the document. This overrides the value of ‘input` if it is a IRI. If not specified and `input` is not an IRI, the base IRI defaults to the current document IRI if in a browser context, or the empty string if there is no document context.

  • :documentLoader (Proc) —

    The callback of the loader to be used to retrieve remote documents and contexts. If specified, it must be used to retrieve remote documents and contexts; otherwise, if not specified, the processor’s built-in loader must be used. See API.documentLoader for the method signature.

  • :prefixes (Hash{Symbol => String}) —

    See ‘RDF::Reader#initialize`

  • :simple_compact_iris (Boolean) — default: false —

    When compacting IRIs, do not use terms with expanded term definitions

  • :vocab (String, #to_s) —

    Initial value for @vocab

  • :language (String, #to_s) —

    Initial value for @langauge

Yields:

  • (ec)

Yield Parameters:



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# File 'lib/json/ld/context.rb', line 160

def initialize(options = {})
  if options[:base]
    @base = @doc_base = RDF::URI(options[:base])
    @doc_base.canonicalize!
    @doc_base.fragment = nil
    @doc_base.query = nil
  end
  options[:documentLoader] ||= JSON::LD::API.method(:documentLoader)
  @term_definitions = {}
  @iri_to_term = {
    RDF.to_uri.to_s => "rdf",
    RDF::XSD.to_uri.to_s => "xsd"
  }
  @namer = BlankNodeMapper.new("t")

  @options = options

  # Load any defined prefixes
  (options[:prefixes] || {}).each_pair do |k, v|
    next if k.nil?
    @iri_to_term[v.to_s] = k
    @term_definitions[k.to_s] = TermDefinition.new(k, v.to_s)
    @term_definitions[k.to_s].simple = true
  end

  self.vocab = options[:vocab] if options[:vocab]
  self.default_language = options[:language] if options[:language]

  #debug("init") {"iri_to_term: #{iri_to_term.inspect}"}
  
  yield(self) if block_given?
end

Instance Attribute Details

#base ⇒ RDF::URI

The base.

Returns:

  • (RDF::URI) —

    Current base IRI, used for expanding relative IRIs.



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# File 'lib/json/ld/context.rb', line 99

def base
  @base
end

#context_base ⇒ RDF::URI

Returns base IRI of the context, if loaded remotely. XXX.

Returns:

  • (RDF::URI) —

    base IRI of the context, if loaded remotely. XXX



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# File 'lib/json/ld/context.rb', line 107

def context_base
  @context_base
end

#default_language ⇒ String

Default language

This adds a language to plain strings that aren’t otherwise coerced

Returns:

  • (String) 


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# File 'lib/json/ld/context.rb', line 123

def default_language
  @default_language
end

#doc_base ⇒ RDF::URI (readonly)

The base.

Returns:

  • (RDF::URI) —

    Document base IRI, to initialize ‘base`.



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# File 'lib/json/ld/context.rb', line 104

def doc_base
  @doc_base
end

#iri_to_term ⇒ Hash{RDF::URI => String}

Returns Reverse mappings from IRI to term only for terms, not CURIEs XXX.

Returns:

  • (Hash{RDF::URI => String}) —

    Reverse mappings from IRI to term only for terms, not CURIEs XXX



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# File 'lib/json/ld/context.rb', line 115

def iri_to_term
  @iri_to_term
end

#namer ⇒ BlankNodeNamer

Returns:



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# File 'lib/json/ld/context.rb', line 140

def namer
  @namer
end

#options ⇒ Hash{Symbol => Object}

Returns Global options used in generating IRIs.

Returns:

  • (Hash{Symbol => Object}) —

    Global options used in generating IRIs



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# File 'lib/json/ld/context.rb', line 133

def options
  @options
end

#provided_context ⇒ Context

Returns A context provided to us that we can use without re-serializing XXX.

Returns:

  • (Context) —

    A context provided to us that we can use without re-serializing XXX



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# File 'lib/json/ld/context.rb', line 136

def provided_context
  @provided_context
end

#term_definitions ⇒ Hash{String => TermDefinition} (readonly)

Term definitions

Returns:



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# File 'lib/json/ld/context.rb', line 112

def term_definitions
  @term_definitions
end

#vocab ⇒ RDF::URI

Default vocabulary

Sets the default vocabulary used for expanding terms which aren’t otherwise absolute IRIs

Returns:

  • (RDF::URI) 


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# File 'lib/json/ld/context.rb', line 130

def vocab
  @vocab
end

Instance Method Details

#compact_iri(iri, options = {}) ⇒ String

Compacts an absolute IRI to the shortest matching term or compact IRI

Parameters:

  • iri (RDF::URI)
  • options (Hash{Symbol => Object}) (defaults to: {}) —

    ({})

Options Hash (options):

  • :value (Object) —

    Value, used to select among various maps for the same IRI

  • :vocab (Boolean) —

    specifies whether the passed iri should be compacted using the active context’s vocabulary mapping

  • :reverse (Boolean) —

    specifies whether a reverse property is being compacted

Returns:

  • (String) —

    compacted form of IRI

See Also:



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# File 'lib/json/ld/context.rb', line 801

def compact_iri(iri, options = {})
  return if iri.nil?
  iri = iri.to_s
  debug("compact_iri(#{iri.inspect}", options) {options.inspect} unless options[:quiet]
  depth(options) do

    value = options.fetch(:value, nil)

    if options[:vocab] && inverse_context.has_key?(iri)
      debug("") {"vocab and key in inverse context"} unless options[:quiet]
      default_language = self.default_language || @none
      containers = []
      tl, tl_value = "@language", "@null"
      containers << '@index' if index?(value)
      if options[:reverse]
        tl, tl_value = "@type", "@reverse"
        containers << '@set'
      elsif list?(value)
        debug("") {"list(#{value.inspect})"} unless options[:quiet]
        # if value is a list object, then set type/language and type/language value to the most specific values that work for all items in the list as follows:
        containers << "@list" unless index?(value)
        list = value['@list']
        common_type = nil
        common_language = default_language if list.empty?
        list.each do |item|
          item_language, item_type = "@none", "@none"
          if value?(item)
            if item.has_key?('@language')
              item_language = item['@language']
            elsif item.has_key?('@type')
              item_type = item['@type']
            else
              item_language = "@null"
            end
          else
            item_type = '@id'
          end
          common_language ||= item_language
          if item_language != common_language && value?(item)
            debug("") {"-- #{item_language} conflicts with #{common_language}, use @none"} unless options[:quiet]
            common_language = '@none'
          end
          common_type ||= item_type
          if item_type != common_type
            common_type = '@none'
            debug("") {"#{item_type} conflicts with #{common_type}, use @none"} unless options[:quiet]
          end
        end

        common_language ||= '@none'
        common_type ||= '@none'
        debug("") {"common type: #{common_type}, common language: #{common_language}"} unless options[:quiet]
        if common_type != '@none'
          tl, tl_value = '@type', common_type
        else
          tl_value = common_language
        end
        debug("") {"list: containers: #{containers.inspect}, type/language: #{tl.inspect}, type/language value: #{tl_value.inspect}"} unless options[:quiet]
      else
        if value?(value)
          if value.has_key?('@language') && !index?(value)
            tl_value = value['@language']
            containers << '@language'
          elsif value.has_key?('@type')
            tl_value = value['@type']
            tl = '@type'
          end
        else
          tl, tl_value = '@type', '@id'
        end
        containers << '@set'
        debug("") {"value: containers: #{containers.inspect}, type/language: #{tl.inspect}, type/language value: #{tl_value.inspect}"} unless options[:quiet]
      end

      containers << '@none'
      tl_value ||= '@null'
      preferred_values = []
      preferred_values << '@reverse' if tl_value == '@reverse'
      if %w(@id @reverse).include?(tl_value) && value.is_a?(Hash) && value.has_key?('@id')
        t_iri = compact_iri(value['@id'], :vocab => true, :document_relative => true)
        if (r_td = term_definitions[t_iri]) && r_td.id == value['@id']
          preferred_values.concat(%w(@vocab @id @none))
        else
          preferred_values.concat(%w(@id @vocab @none))
        end
      else
        preferred_values.concat([tl_value, '@none'])
      end
      debug("") {"preferred_values: #{preferred_values.inspect}"} unless options[:quiet]
      if p_term = select_term(iri, containers, tl, preferred_values)
        debug("") {"=> term: #{p_term.inspect}"} unless options[:quiet]
        return p_term
      end
    end

    # At this point, there is no simple term that iri can be compacted to. If vocab is true and active context has a vocabulary mapping:
    if options[:vocab] && vocab && iri.start_with?(vocab) && iri.length > vocab.length
      suffix = iri[vocab.length..-1]
      debug("") {"=> vocab suffix: #{suffix.inspect}"} unless options[:quiet]
      return suffix unless term_definitions.has_key?(suffix)
    end

    # The iri could not be compacted using the active context's vocabulary mapping. Try to create a compact IRI, starting by initializing compact IRI to null. This variable will be used to tore the created compact IRI, if any.
    candidates = []

    term_definitions.each do |term, td|
      next if term.include?(":")
      next if td.nil? || td.id.nil? || td.id == iri || !iri.start_with?(td.id)

      # Also skip term if it was not a simple term and the :simple_compact_iris flag is true
      next if @options[:simple_compact_iris] && !td.simple?

      suffix = iri[td.id.length..-1]
      ciri = "#{term}:#{suffix}"
      candidates << ciri unless value && term_definitions.has_key?(ciri)
    end

    if !candidates.empty?
      debug("") {"=> compact iri: #{candidates.term_sort.first.inspect}"} unless options[:quiet]
      return candidates.term_sort.first
    end

    # If we still don't have any terms and we're using standard_prefixes,
    # try those, and add to mapping
    if @options[:standard_prefixes]
      candidates = RDF::Vocabulary.
        select {|v| iri.start_with?(v.to_uri.to_s) && iri != v.to_uri.to_s}.
        map do |v|
          prefix = v.__name__.to_s.split('::').last.downcase
          set_mapping(prefix, v.to_uri.to_s)
          iri.sub(v.to_uri.to_s, "#{prefix}:").sub(/:$/, '')
        end

      if !candidates.empty?
        debug("") {"=> standard prefies: #{candidates.term_sort.first.inspect}"} unless options[:quiet]
        return candidates.term_sort.first
      end
    end

    if !options[:vocab]
      # transform iri to a relative IRI using the document's base IRI
      iri = remove_base(iri)
      debug("") {"=> relative iri: #{iri.inspect}"} unless options[:quiet]
      return iri
    else
      debug("") {"=> absolute iri: #{iri.inspect}"} unless options[:quiet]
      return iri
    end
  end
end

#compact_value(property, value, options = {}) ⇒ Hash

Compact a value

FIXME: revisit the specification version of this.

Parameters:

  • property (String) —

    Associated property used to find coercion rules

  • value (Hash) —

    Value (literal or IRI), in full object representation, to be compacted

  • options (Hash{Symbol => Object}) (defaults to: {})

Returns:

  • (Hash) —

    Object representation of value

Raises:

See Also:



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# File 'lib/json/ld/context.rb', line 1045

def compact_value(property, value, options = {})

  depth(options) do
    debug("compact_value") {"property: #{property.inspect}, value: #{value.inspect}"}

    num_members = value.keys.length

    num_members -= 1 if index?(value) && container(property) == '@index'
    if num_members > 2
      debug("") {"can't compact value with # members > 2"}
      return value
    end

    result = case
    when coerce(property) == '@id' && value.has_key?('@id') && num_members == 1
      # Compact an @id coercion
      debug("") {" (@id & coerce)"}
      compact_iri(value['@id'])
    when coerce(property) == '@vocab' && value.has_key?('@id') && num_members == 1
      # Compact an @id coercion
      debug("") {" (@id & coerce & vocab)"}
      compact_iri(value['@id'], :vocab => true)
    when value.has_key?('@id')
      debug("") {" (@id)"}
      # return value as is
      value
    when value['@type'] && expand_iri(value['@type'], :vocab => true) == coerce(property)
      # Compact common datatype
      debug("") {" (@type & coerce) == #{coerce(property)}"}
      value['@value']
    when value['@language'] && (value['@language'] == language(property))
      # Compact language
      debug("") {" (@language) == #{language(property).inspect}"}
      value['@value']
    when num_members == 1 && !value['@value'].is_a?(String)
      debug("") {" (native)"}
      value['@value']
    when num_members == 1 && default_language.nil? || language(property) == false
      debug("") {" (!@language)"}
      value['@value']
    else
      # Otherwise, use original value
      debug("") {" (no change)"}
      value
    end
    
    # If the result is an object, tranform keys using any term keyword aliases
    if result.is_a?(Hash) && result.keys.any? {|k| self.alias(k) != k}
      debug("") {" (map to key aliases)"}
      new_element = {}
      result.each do |k, v|
        new_element[self.alias(k)] = v
      end
      result = new_element
    end

    debug("") {"=> #{result.inspect}"}
    result
  end
end

#container(term) ⇒ String

Retrieve container mapping, add it if ‘value` is provided

Parameters:

  • term (Term, #to_s) —

    in unexpanded form

Returns:

  • (String) 


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# File 'lib/json/ld/context.rb', line 660

def container(term)
  return '@set' if term == '@graph'
  return term if KEYWORDS.include?(term)
  term = find_definition(term)
  term && term.container_mapping
end

#create_term_definition(local_context, term, defined) ⇒ Object

Create Term Definition

Term definitions are created by parsing the information in the given local context for the given term. If the given term is a compact IRI, it may omit an IRI mapping by depending on its prefix having its own term definition. If the prefix is a key in the local context, then its term definition must first be created, through recursion, before continuing. Because a term definition can depend on other term definitions, a mechanism must be used to detect cyclical dependencies. The solution employed here uses a map, defined, that keeps track of whether or not a term has been defined or is currently in the process of being defined. This map is checked before any recursion is attempted.

After all dependencies for a term have been defined, the rest of the information in the local context for the given term is taken into account, creating the appropriate IRI mapping, container mapping, and type mapping or language mapping for the term.

Parameters:

  • local_context (Hash)
  • term (String)
  • defined (Hash)

Raises:

  • (JsonLdError) —

    Represents a cyclical term dependency

See Also:



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# File 'lib/json/ld/context.rb', line 369

def create_term_definition(local_context, term, defined)
  # Expand a string value, unless it matches a keyword
  debug("create_term_definition") {"term = #{term.inspect}"}

  # If defined contains the key term, then the associated value must be true, indicating that the term definition has already been created, so return. Otherwise, a cyclical term definition has been detected, which is an error.
  case defined[term]
  when TrueClass then return
  when nil
    defined[term] = false
  else
    raise JsonLdError::CyclicIRIMapping, "Cyclical term dependency found: #{term.inspect}"
  end

  # Since keywords cannot be overridden, term must not be a keyword. Otherwise, an invalid value has been detected, which is an error.
  if KEYWORDS.include?(term) && !%w(@vocab @language).include?(term)
    raise JsonLdError::KeywordRedefinition, "term must not be a keyword: #{term.inspect}" if
      @options[:validate]
  elsif !term_valid?(term) && @options[:validate]
    raise JsonLdError::InvalidTermDefinition, "term is invalid: #{term.inspect}"
  end

  # Remove any existing term definition for term in active context.
  term_definitions.delete(term)

  # Initialize value to a the value associated with the key term in local context.
  value = local_context.fetch(term, false)
  simple_term = value.is_a?(String)
  value = {'@id' => value} if value.is_a?(String)

  case value
  when nil, {'@id' => nil}
    # If value equals null or value is a JSON object containing the key-value pair (@id-null), then set the term definition in active context to null, set the value associated with defined's key term to true, and return.
    debug("") {"=> nil"}
    term_definitions[term] = TermDefinition.new(term)
    defined[term] = true
    return
  when Hash
    debug("") {"Hash[#{term.inspect}] = #{value.inspect}"}
    definition = TermDefinition.new(term)
    definition.simple = simple_term

    if value.has_key?('@type')
      type = value['@type']
      # SPEC FIXME: @type may be nil
      type = case type
      when nil
        type
      when String
        begin
          expand_iri(type, :vocab => true, :documentRelative => false, :local_context => local_context, :defined => defined)
        rescue JsonLdError::InvalidIRIMapping
          raise JsonLdError::InvalidTypeMapping, "invalid mapping for '@type': #{type.inspect} on term #{term.inspect}"
        end
      else
        :error
      end
      unless %w(@id @vocab).include?(type) || type.is_a?(RDF::URI) && type.absolute?
        raise JsonLdError::InvalidTypeMapping, "unknown mapping for '@type': #{type.inspect} on term #{term.inspect}"
      end
      debug("") {"type_mapping: #{type.inspect}"}
      definition.type_mapping = type
    end

    if value.has_key?('@reverse')
      raise JsonLdError::InvalidReverseProperty, "unexpected key in #{value.inspect} on term #{term.inspect}" if
        value.keys.any? {|k| %w(@id).include?(k)}
      raise JsonLdError::InvalidIRIMapping, "expected value of @reverse to be a string: #{value['@reverse'].inspect} on term #{term.inspect}" unless
        value['@reverse'].is_a?(String)

      # Otherwise, set the IRI mapping of definition to the result of using the IRI Expansion algorithm, passing active context, the value associated with the @reverse key for value, true for vocab, true for document relative, local context, and defined. If the result is not an absolute IRI, i.e., it contains no colon (:), an invalid IRI mapping error has been detected and processing is aborted.
      definition.id =  expand_iri(value['@reverse'],
                                  :vocab => true,
                                  :documentRelative => true,
                                  :local_context => local_context,
                                  :defined => defined)
      raise JsonLdError::InvalidIRIMapping, "non-absolute @reverse IRI: #{definition.id} on term #{term.inspect}" unless
        definition.id.is_a?(RDF::URI) && definition.id.absolute?

      # If value contains an @container member, set the container mapping of definition to its value; if its value is neither @set, nor @index, nor null, an invalid reverse property error has been detected (reverse properties only support set- and index-containers) and processing is aborted.
      if (container = value.fetch('@container', false))
        raise JsonLdError::InvalidReverseProperty,
              "unknown mapping for '@container' to #{container.inspect} on term #{term.inspect}" unless
               ['@set', '@index', nil].include?(container)
        definition.container_mapping = container
      end
      definition.reverse_property = true
    elsif value.has_key?('@id') && value['@id'] != term
      raise JsonLdError::InvalidIRIMapping, "expected value of @id to be a string: #{value['@id'].inspect} on term #{term.inspect}" unless
        value['@id'].is_a?(String)
      definition.id = expand_iri(value['@id'],
        :vocab => true,
        :documentRelative => true,
        :local_context => local_context,
        :defined => defined)
      raise JsonLdError::InvalidKeywordAlias, "expected value of @id to not be @context on term #{term.inspect}" if
        definition.id == '@context'
    elsif term.include?(':')
      # If term is a compact IRI with a prefix that is a key in local context then a dependency has been found. Use this algorithm recursively passing active context, local context, the prefix as term, and defined.
      prefix, suffix = term.split(':')
      depth {create_term_definition(local_context, prefix, defined)} if local_context.has_key?(prefix)

      definition.id = if td = term_definitions[prefix]
        # If term's prefix has a term definition in active context, set the IRI mapping for definition to the result of concatenating the value associated with the prefix's IRI mapping and the term's suffix.
        td.id + suffix
      else
        # Otherwise, term is an absolute IRI. Set the IRI mapping for definition to term
        term
      end
      debug("") {"=> #{definition.id}"}
    else
      # Otherwise, active context must have a vocabulary mapping, otherwise an invalid value has been detected, which is an error. Set the IRI mapping for definition to the result of concatenating the value associated with the vocabulary mapping and term.
      raise JsonLdError::InvalidIRIMapping, "relative term definition without vocab: #{term} on term #{term.inspect}" unless vocab
      definition.id = vocab + term
      debug("") {"=> #{definition.id}"}
    end

    @iri_to_term[definition.id] = term if simple_term && definition.id

    if value.has_key?('@container')
      container = value['@container']
      raise JsonLdError::InvalidContainerMapping, "unknown mapping for '@container' to #{container.inspect} on term #{term.inspect}" unless %w(@list @set @language @index).include?(container)
      debug("") {"container_mapping: #{container.inspect}"}
      definition.container_mapping = container
    end

    if value.has_key?('@language')
      language = value['@language']
      raise JsonLdError::InvalidLanguageMapping, "language must be null or a string, was #{language.inspect}} on term #{term.inspect}" unless language.nil? || (language || "").is_a?(String)
      language = language.downcase if language.is_a?(String)
      debug("") {"language_mapping: #{language.inspect}"}
      definition.language_mapping = language || false
    end

    term_definitions[term] = definition
    defined[term] = true
  else
    raise JsonLdError::InvalidTermDefinition, "Term definition for #{term.inspect} is an #{value.class} on term #{term.inspect}"
  end
end

#dup ⇒ Object 



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# File 'lib/json/ld/context.rb', line 1115

def dup
  # Also duplicate mappings, coerce and list
  that = self
  ec = super
  ec.instance_eval do
    @term_definitions = that.term_definitions.dup
    @iri_to_term = that.iri_to_term.dup
  end
  ec
end

#empty? ⇒ Boolean

Initial context, without mappings, vocab or default language

Returns:

  • (Boolean) 


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# File 'lib/json/ld/context.rb', line 197

def empty?
  @term_definitions.empty? && self.vocab.nil? && self.default_language.nil?
end

#expand_iri(value, options = {}) ⇒ RDF::URI, String

Expand an IRI. Relative IRIs are expanded against any document base.

Parameters:

  • value (String) —

    A keyword, term, prefix:suffix or possibly relative IRI

  • options (Hash{Symbol => Object}) (defaults to: {})

Options Hash (options):

  • documentRelative (Boolean) — default: false
  • vocab (Boolean) — default: false
  • local_context (Hash) —

    Used during Context Processing.

  • defined (Hash) —

    Used during Context Processing.

Returns:

  • (RDF::URI, String) —

    IRI or String, if it’s a keyword

Raises:

See Also:



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# File 'lib/json/ld/context.rb', line 723

def expand_iri(value, options = {})
  return value unless value.is_a?(String)

  return value if KEYWORDS.include?(value)
  depth(options) do
    debug("expand_iri") {"value: #{value.inspect}"} unless options[:quiet]
    local_context = options[:local_context]
    defined = options.fetch(:defined, {})

    # If local context is not null, it contains a key that equals value, and the value associated with the key that equals value in defined is not true, then invoke the Create Term Definition subalgorithm, passing active context, local context, value as term, and defined. This will ensure that a term definition is created for value in active context during Context Processing.
    if local_context && local_context.has_key?(value) && !defined[value]
      depth {create_term_definition(local_context, value, defined)}
    end

    # If vocab is true and the active context has a term definition for value, return the associated IRI mapping.
    if options[:vocab] && (v_td = term_definitions[value])
      debug("") {"match with #{v_td.id}"} unless options[:quiet]
      return v_td.id
    end

    # If value contains a colon (:), it is either an absolute IRI or a compact IRI:
    if value.include?(':')
      prefix, suffix = value.split(':', 2)
      debug("") {"prefix: #{prefix.inspect}, suffix: #{suffix.inspect}, vocab: #{vocab.inspect}"} unless options[:quiet]

      # If prefix is underscore (_) or suffix begins with double-forward-slash (//), return value as it is already an absolute IRI or a blank node identifier.
      return RDF::Node.new(namer.get_sym(suffix)) if prefix == '_'
      return RDF::URI(value) if suffix[0,2] == '//'

      # If local context is not null, it contains a key that equals prefix, and the value associated with the key that equals prefix in defined is not true, invoke the Create Term Definition algorithm, passing active context, local context, prefix as term, and defined. This will ensure that a term definition is created for prefix in active context during Context Processing.
      if local_context && local_context.has_key?(prefix) && !defined[prefix]
        create_term_definition(local_context, prefix, defined)
      end

      # If active context contains a term definition for prefix, return the result of concatenating the IRI mapping associated with prefix and suffix.
      result = if (td = term_definitions[prefix])
        result = td.id + suffix
      else
        # (Otherwise) Return value as it is already an absolute IRI.
        RDF::URI(value)
      end

      debug("") {"=> #{result.inspect}"} unless options[:quiet]
      return result
    end
    debug("") {"=> #{result.inspect}"} unless options[:quiet]

    result = if options[:vocab] && vocab
      # If vocab is true, and active context has a vocabulary mapping, return the result of concatenating the vocabulary mapping with value.
      vocab + value
    elsif options[:documentRelative] && base = options.fetch(:base, self.base)
      # Otherwise, if document relative is true, set value to the result of resolving value against the base IRI. Only the basic algorithm in section 5.2 of [RFC3986] is used; neither Syntax-Based Normalization nor Scheme-Based Normalization are performed. Characters additionally allowed in IRI references are treated in the same way that unreserved characters are treated in URI references, per section 6.5 of [RFC3987].
      RDF::URI(base).join(value)
    elsif local_context && RDF::URI(value).relative?
      # If local context is not null and value is not an absolute IRI, an invalid IRI mapping error has been detected and processing is aborted.
      raise JSON::LD::JsonLdError::InvalidIRIMapping, "not an absolute IRI: #{value}"
    else
      RDF::URI(value)
    end
    debug("") {"=> #{result}"} unless options[:quiet]
    result
  end
end

#expand_value(property, value, options = {}) ⇒ Hash

If active property has a type mapping in the active context set to @id or @vocab, a JSON object with a single member @id whose value is the result of using the IRI Expansion algorithm on value is returned.

Otherwise, the result will be a JSON object containing an @value member whose value is the passed value. Additionally, an @type member will be included if there is a type mapping associated with the active property or an @language member if value is a string and there is language mapping associated with the active property.

Parameters:

  • property (String) —

    Associated property used to find coercion rules

  • value (Hash, String) —

    Value (literal or IRI) to be expanded

  • options (Hash{Symbol => Object}) (defaults to: {})

Options Hash (options):

  • :useNativeTypes (Boolean) — default: false —

    use native representations

Returns:

  • (Hash) —

    Object representation of value

Raises:

  • (RDF::ReaderError) —

    if the iri cannot be expanded

See Also:



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# File 'lib/json/ld/context.rb', line 967

def expand_value(property, value, options = {})
  options = {:useNativeTypes => false}.merge(options)
  depth(options) do
    debug("expand_value") {"property: #{property.inspect}, value: #{value.inspect}"}

    # If the active property has a type mapping in active context that is @id, return a new JSON object containing a single key-value pair where the key is @id and the value is the result of using the IRI Expansion algorithm, passing active context, value, and true for document relative.
    if (td = term_definitions.fetch(property, TermDefinition.new(property))) && td.type_mapping == '@id'
      debug("") {"as relative IRI: #{value.inspect}"}
      return {'@id' => expand_iri(value, :documentRelative => true).to_s}
    end

    # If active property has a type mapping in active context that is @vocab, return a new JSON object containing a single key-value pair where the key is @id and the value is the result of using the IRI Expansion algorithm, passing active context, value, true for vocab, and true for document relative.
    if td.type_mapping == '@vocab'
      debug("") {"as vocab IRI: #{value.inspect}"}
      return {'@id' => expand_iri(value, :vocab => true, :documentRelative => true).to_s}
    end

    value = RDF::Literal(value) if
      value.is_a?(Date) ||
      value.is_a?(DateTime) ||
      value.is_a?(Time)

    result = case value
    when RDF::URI, RDF::Node
      debug("URI | BNode") { value.to_s }
      {'@id' => value.to_s}
    when RDF::Literal
      debug("Literal") {"datatype: #{value.datatype.inspect}"}
      res = {}
      if options[:useNativeTypes] && [RDF::XSD.boolean, RDF::XSD.integer, RDF::XSD.double].include?(value.datatype)
        res['@value'] = value.object
        res['@type'] = uri(coerce(property)) if coerce(property)
      else
        value.canonicalize! if value.datatype == RDF::XSD.double
        res['@value'] = value.to_s
        if coerce(property)
          res['@type'] = uri(coerce(property)).to_s
        elsif value.has_datatype?
          res['@type'] = uri(value.datatype).to_s
        elsif value.has_language? || language(property)
          res['@language'] = (value.language || language(property)).to_s
        end
      end
      res
    else
      # Otherwise, initialize result to a JSON object with an @value member whose value is set to value.
      res = {'@value' => value}

      if td.type_mapping
        res['@type'] = td.type_mapping.to_s
      elsif value.is_a?(String)
        if td.language_mapping
          res['@language'] = td.language_mapping
        elsif default_language && td.language_mapping.nil?
          res['@language'] = default_language
        end
      end
      res
    end

    debug("") {"=> #{result.inspect}"}
    result
  end
end

#find_definition(term) ⇒ Term

Find a term definition

Parameters:

  • term (Term, #to_s) —

    in unexpanded form

Returns:

  • (Term) 


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# File 'lib/json/ld/context.rb', line 651

def find_definition(term)
  term.is_a?(TermDefinition) ? term : term_definitions[term.to_s]
end

#from_vocabulary(graph) ⇒ self

Build a context from an RDF::Vocabulary definition.

Examples:

building from an external vocabulary definition


g = RDF::Graph.load("http://schema.org/docs/schema_org_rdfa.html")

context = JSON::LD::Context.new.from_vocabulary(g,
      vocab: "http://schema.org/",
      prefixes: {schema: "http://schema.org/"},
      language: "en")

Parameters:

  • graph (RDF::Queryable)

Returns:

  • (self) 


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# File 'lib/json/ld/context.rb', line 567

def from_vocabulary(graph)
  statements = {}
  ranges = {}

  # Add term definitions for each class and property not in schema:, and
  # for those properties having an object range
  graph.each do |statement|
    next if statement.subject.node?
    (statements[statement.subject] ||= []) << statement

    # Keep track of predicate ranges
    if [RDF::RDFS.range, RDF::SCHEMA.rangeIncludes].include?(statement.predicate) 
      (ranges[statement.subject] ||= []) << statement.object
    end
  end

  # Add term definitions for each class and property not in vocab, and
  # for those properties having an object range
  statements.each do |subject, values|
    types = values.select {|v| v.predicate == RDF.type}.map(&:object)
    is_property = types.any? {|t| t.to_s.include?("Property")}
    
    term = subject.to_s.split(/[\/\#]/).last

    if !is_property
      # Ignore if there's a default voabulary and this is not a property
      next if vocab && subject.to_s.start_with?(vocab)

      # otherwise, create a term definition
      td = term_definitions[term] = TermDefinition.new(term, subject.to_s)
    else
      prop_ranges = ranges.fetch(subject, [])
      # If any range is empty or member of range includes rdfs:Literal or schema:Text
      next if vocab && prop_ranges.empty? ||
                       prop_ranges.include?(RDF::SCHEMA.Text) ||
                       prop_ranges.include?(RDF::RDFS.Literal)
      td = term_definitions[term] = TermDefinition.new(term, subject.to_s)

      # Set context typing based on first element in range
      case r = prop_ranges.first
      when RDF::XSD.string
        if self.default_language
          td.language_mapping = false
        end
      when RDF::XSD.boolean, RDF::SCHEMA.Boolean, RDF::XSD.date, RDF::SCHEMA.Date,
        RDF::XSD.dateTime, RDF::SCHEMA.DateTime, RDF::XSD.time, RDF::SCHEMA.Time,
        RDF::XSD.duration, RDF::SCHEMA.Duration, RDF::XSD.decimal, RDF::SCHEMA.Number,
        RDF::XSD.float, RDF::SCHEMA.Float, RDF::XSD.integer, RDF::SCHEMA.Integer
        td.type_mapping = r
        td.simple = false
      else
        # It's an object range (includes schema:URL)
        td.type_mapping = '@id'
      end
    end
  end

  self
end

#inspect ⇒ Object 



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# File 'lib/json/ld/context.rb', line 1106

def inspect
  v = %w([Context)
  v << "base=#{base}" if base
  v << "vocab=#{vocab}" if vocab
  v << "def_language=#{default_language}" if default_language
  v << "term_definitions[#{term_definitions.length}]=#{term_definitions}"
  v.join(" ") + "]"
end

#language(term) ⇒ String

Retrieve the language associated with a term, or the default language otherwise

Parameters:

  • term (Term, #to_s) —

    in unexpanded form

Returns:

  • (String) 


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# File 'lib/json/ld/context.rb', line 671

def language(term)
  term = find_definition(term)
  lang = term && term.language_mapping
  lang.nil? ? @default_language : lang
end

#parse(local_context, remote_contexts = []) ⇒ Object

Create an Evaluation Context

When processing a JSON-LD data structure, each processing rule is applied using information provided by the active context. This section describes how to produce an active context.

The active context contains the active term definitions which specify how properties and values have to be interpreted as well as the current base IRI, the vocabulary mapping and the default language. Each term definition consists of an IRI mapping, a boolean flag reverse property, an optional type mapping or language mapping, and an optional container mapping. A term definition can not only be used to map a term to an IRI, but also to map a term to a keyword, in which case it is referred to as a keyword alias.

When processing, the active context is initialized without any term definitions, vocabulary mapping, or default language. If a local context is encountered during processing, a new active context is created by cloning the existing active context. Then the information from the local context is merged into the new active context. Given that local contexts may contain references to remote contexts, this includes their retrieval.

Parameters:

Raises:

  • (JsonLdError) —

    on a remote context load error, syntax error, or a reference to a term which is not defined.

See Also:



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# File 'lib/json/ld/context.rb', line 256

def parse(local_context, remote_contexts = [])
  result = self.dup
  result.provided_context = local_context if self.empty?

  local_context = [local_context] unless local_context.is_a?(Array)

  local_context.each do |context|
    depth do
      case context
      when nil
        # 3.1 If niil, set to a new empty context
        result = Context.new(options)
      when Context
         debug("parse") {"context: #{context.inspect}"}
         result = context.dup
      when IO, StringIO
        debug("parse") {"io: #{context}"}
        # Load context document, if it is a string
        begin
          ctx = JSON.load(context)
          raise JSON::LD::JsonLdError::InvalidRemoteContext, "Context missing @context key" if @options[:validate] && ctx['@context'].nil?
          result = parse(ctx["@context"] ? ctx["@context"].dup : {})
          result.provided_context = ctx["@context"] if [context] == local_context
          result
        rescue JSON::ParserError => e
          debug("parse") {"Failed to parse @context from remote document at #{context}: #{e.message}"}
          raise JSON::LD::JsonLdError::InvalidRemoteContext, "Failed to parse remote context at #{context}: #{e.message}" if @options[:validate]
          self.dup
        end
      when String, RDF::URI
        debug("parse") {"remote: #{context}, base: #{result.context_base || result.base}"}
        # Load context document, if it is a string
        # 3.2.1) Set context to the result of resolving value against the base IRI which is established as specified in section 5.1 Establishing a Base URI of [RFC3986]. Only the basic algorithm in section 5.2 of [RFC3986] is used; neither Syntax-Based Normalization nor Scheme-Based Normalization are performed. Characters additionally allowed in IRI references are treated in the same way that unreserved characters are treated in URI references, per section 6.5 of [RFC3987].
        context = RDF::URI(result.context_base || result.base).join(context)

        raise JsonLdError::RecursiveContextInclusion, "#{context}" if remote_contexts.include?(context.to_s)
        remote_contexts << context.to_s

        context_no_base = self.dup
        context_no_base.base = nil
        context_no_base.context_base = context.to_s

        begin
          @options[:documentLoader].call(context.to_s) do |remote_doc|
            # 3.2.5) Dereference context. If the dereferenced document has no top-level JSON object with an @context member, an invalid remote context has been detected and processing is aborted; otherwise, set context to the value of that member.
            jo = case remote_doc.document
            when String then JSON.parse(remote_doc.document)
            else remote_doc.document
            end
            raise JsonLdError::InvalidRemoteContext, "#{context}" unless jo.is_a?(Hash) && jo.has_key?('@context')
            context = jo['@context']
            if @options[:processingMode] == "json-ld-1.0"
              context_no_base.provided_context = context.dup
            end
          end
        rescue JsonLdError
          raise
        rescue Exception => e
          debug("parse") {"Failed to retrieve @context from remote document at #{context_no_base.context_base.inspect}: #{e.message}"}
          raise JsonLdError::LoadingRemoteContextFailed, "#{context_no_base.context_base}", e.backtrace
        end

        # 3.2.6) Set context to the result of recursively calling this algorithm, passing context no base for active context, context for local context, and remote contexts.
        context = context_no_base.parse(context, remote_contexts.dup)
        context.provided_context = result.provided_context
        context.base ||= result.base
        result = context
        debug("parse") {"=> provided_context: #{context.inspect}"}
      when Hash
        # If context has a @vocab member: if its value is not a valid absolute IRI or null trigger an INVALID_VOCAB_MAPPING error; otherwise set the active context's vocabulary mapping to its value and remove the @vocab member from context.
        context = context.dup # keep from modifying a hash passed as a param
        {
          '@base' => :base=,
          '@language' => :default_language=,
          '@vocab'    => :vocab=
        }.each do |key, setter|
          v = context.fetch(key, false)
          unless v == false
            context.delete(key)
            debug("parse") {"Set #{key} to #{v.inspect}"}
            result.send(setter, v)
          end
        end

        defined = {}
      # For each key-value pair in context invoke the Create Term Definition subalgorithm, passing result for active context, context for local context, key, and defined
        depth do
          context.keys.each do |key|
            result.create_term_definition(context, key, defined)
          end
        end
      else
        # 3.3) If context is not a JSON object, an invalid local context error has been detected and processing is aborted.
        raise JsonLdError::InvalidLocalContext, context.inspect
      end
    end
  end
  result
end

#reverse?(term) ⇒ Boolean

Is this a reverse term

Parameters:

  • term (Term, #to_s) —

    in unexpanded form

Returns:

  • (Boolean) 


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# File 'lib/json/ld/context.rb', line 681

def reverse?(term)
  term = find_definition(term)
  term && term.reverse_property
end

#reverse_term(term) ⇒ Term

Given a term or IRI, find a reverse term definition matching that term. If the term is already reversed, find a non-reversed version.

Parameters:

  • term (Term, #to_s)

Returns:

  • (Term) —

    related term definition



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# File 'lib/json/ld/context.rb', line 691

def reverse_term(term)
  # Direct lookup of term
  term = term_definitions[term.to_s] if term_definitions.has_key?(term.to_s) && !term.is_a?(TermDefinition)

  # Lookup term, assuming term is an IRI
  unless term.is_a?(TermDefinition)
    td = term_definitions.values.detect {|t| t.id == term.to_s}

    # Otherwise create a temporary term definition
    term = td || TermDefinition.new(term.to_s, expand_iri(term, vocab:true))
  end

  # Now, return a term, which reverses this term
  term_definitions.values.detect {|t| t.id == term.id && t.reverse_property != term.reverse_property}
end

#serialize(options = {}) ⇒ Hash

Generate @context

If a context was supplied in global options, use that, otherwise, generate one from this representation.

Parameters:

  • options (Hash{Symbol => Object}) (defaults to: {}) —

    ({})

Returns:

  • (Hash) 


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# File 'lib/json/ld/context.rb', line 517

def serialize(options = {})
  depth(options) do
    # FIXME: not setting provided_context now
    use_context = case provided_context
    when String, RDF::URI
      debug "serlialize: reuse context: #{provided_context.inspect}"
      provided_context.to_s
    when Hash, Array
      debug "serlialize: reuse context: #{provided_context.inspect}"
      provided_context
    else
      debug("serlialize: generate context")
      debug("") {"=> context: #{inspect}"}
      ctx = {}
      ctx['@base'] = base.to_s if base && base != doc_base
      ctx['@language'] = default_language.to_s if default_language
      ctx['@vocab'] = vocab.to_s if vocab

      # Term Definitions
      term_definitions.keys.sort.each do |term|
        defn = term_definitions[term].to_context_definition(self)
        ctx[term] = defn if defn
      end

      debug("") {"start_doc: context=#{ctx.inspect}"}
      ctx
    end

    # Return hash with @context, or empty
    r = {}
    r['@context'] = use_context unless use_context.nil? || use_context.empty?
    r
  end
end

#set_mapping(term, value) ⇒ TermDefinition

Set term mapping

Parameters:

  • term (#to_s)
  • value (RDF::URI, String, nil)

Returns:



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# File 'lib/json/ld/context.rb', line 633

def set_mapping(term, value)
  debug("") {"map #{term.inspect} to #{value.inspect}"}
  term = term.to_s
  term_definitions[term] = TermDefinition.new(term, value)
  term_definitions[term].simple = true

  term_sym = term.empty? ? "" : term.to_sym
  iri_to_term.delete(term_definitions[term].id.to_s) if term_definitions[term].id.is_a?(String)
  @options[:prefixes][term_sym] = value if @options.has_key?(:prefixes)
  iri_to_term[value.to_s] = term
  term_definitions[term]
end